Electrostatic fields

Suppose a radial electrostatic field is produced by a cylindrical condenser. The trajectory is then circular and the velocity is constantly perpendicular to the field. Thus the centrifugal 

energy dispersion right, angular dispersion. 

Since the trajectory is independent of the mass, the electric field is not a mass analyser, but rather a kinetic energy analyser, just as the magnetic field is a momentum analyser. Note that the electric sector separates the ions according to their kinetic energy. 

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Kirkwood generalized the Onsager reaction field method to arbitrary charge distributions and, for a spherical cavity, obtained the Gibbs free energy of solvation in tenns of a miiltipole expansion of the electrostatic field generated by the charge distribution [12, 1 3]... 

The work fiinction (di) is defined as the minimum work that has to be done to remove an electron from tlie bulk of the material to a sufficient distance outside the surface such that it no longer experiences an interaction with the surface electrostatic field [43, 44 and 45]. In other words, it is the minimum energy required to remove an electron from the... 

The first term represents the forces due to the electrostatic field, the second describes forces that occur at the boundary between solute and solvent regime due to the change of dielectric constant, and the third term describes ionic forces due to the tendency of the ions in solution to move into regions of lower dielectric. Applications of the so-called PBSD method on small model systems and for the interaction of a stretch of DNA with a protein model have been discussed recently ([Elcock et al. 1997]). This simulation technique guarantees equilibrated solvent at each state of the simulation and may therefore avoid some of the problems mentioned in the previous section. Due to the smaller number of particles, the method may also speed up simulations potentially. Still, to be able to simulate long time scale protein motion, the method might ideally be combined with non-equilibrium techniques to enforce conformational transitions. 

Equation (18) is valid when the polarizability of the dielectric is proportional to the electrostatic field strength [4]. The operator V in the Cartesian coordinate system has the form V = dldx,dldy,dldz). 

In the reaction field method, a sphere is constructed around the molecule with a radius equal to the cutoff distance. The interaction with molecules that are within the sphere is calculated explicitly. To this is added the energy of interaction with the medium beyond the sphere, which is rnodelled as a homogeneous medium of dielectric constant g (Figure 6.23). The electrostatic field due to the surrounding dielectric is given by ... 

From these calculated displacements, the contributions to the energy from the ions in re 2a can be determined. Finally, it is necessary to determine the contribution from the io] region 2b. As we have mentioned, these are not included explicitly but are considers polarise due to the electrostatic field from the total charge on the defect. This contribr is gi en by the following summation ... 

For a quantum mechanical calculation, the single point calculation leads to a wave function for the molecular system and considerably more information than just the energy and gradient are available. In principle, any expectation value might be computed. You can get plots of the individual orbitals, the total (or spin) electron density and the electrostatic field around the molecule. You can see the orbital energies in the status line when you plot an orbital. Finally, the log file contains additional information including the dipole moment of the molecule. The level of detail may be controlled by the PrintLevel entry in the chem.ini file. 

The reflectron consists of a series of ring electrodes, on each of which is placed an electric potential. The first ring has the lowest potential and the last ring the highest to produce an electrostatic field that increases from the front end of the electron to the back. 

Electrostatic analyzer. A velocity-focusing device for producing an electrostatic field perpendicular to the direction of ion travel (usually used in combination with a magnetic analyzer for mass analysis). The effect is to bring to a common focus all ions of a given kinetic energy. 

Mattauch-Herzog geometry. An arrangement for a double-focusing mass spectrometer in which a deflection of n/A radians in a radial electrostatic field is followed by a magnetic deflection of nil radians. 

The vector L is so strongly coupled to the electrostatic field and the consequent frequency of precession about the intemuclear axis is so high that the magnitude of L is not defined in other words L is not a good quantum number. Only the component H of the orbital angular momentum along the intemuclear axis is defined, where the quantum number A can take the values... 

The coupling of S to the intemuclear axis is caused not by the electrostatic field, which has no effect on it, but by the magnetic field along the axis due to the orbital motion of the electrons. Figure 7.16(a) shows that the component of S along the intemuclear axis is Ffi. The quantum number F is analogous to Mg in an atom and can take the values... 

Static eliminating devices that ionize the atmosphere around the device are available. Static eliminators are divided into two main groups silent (corona) discharge eliminators, such as inductive eliminators, or high voltage eliminators which initiate an impact ionization of the air by applying strong electrostatic fields, and radioactive eliminators that provide a multitude of ions from independent ion sources (9). 

Recent developments in rotary atomization include the use of semiconductive composites (qv) for the rotary cup permitting the constmction of a unit that does not produce an ignition spark when brought close to a grounded workpiece yet has the transfer efficiencies associated with a rotary atomizer. In addition, the use of the semiconductive material softens the electrostatic field and results in less edge buildup and better penetration into recess areas. Other systems use electronic means to effectively prevent arcing to grounded surfaces. 

From accurate measurements of the Stark effect when electrostatic fields are applied, information regarding the electron distribution is obtained. Further Information on this point is obtained from nuclear quadrupole coupling effects and Zeeman effects (74PMH(6)53). 

The more recent results of Scheme 18 can be summarized as follows the less hindered isomer is formed unless the substituent has a lone pair, the electrostatic field of which enhances the nucleophilicity of the adjacent nitrogen atom. This is true not only for pyridine and pyrazole, but probably also for CHO and C02Et. 

Electrical Precipitators When particles suspended in a gas are exposed to gas ions in an electrostatic field, they will become charged and migrate under the ac tion of the field. The functional mechanisms of electrical precipitation may be listed as follows ... 

Field Strength Whereas the applied potential or voltage is the quantity commonly known, it is the field strength that determines behavior in an electrostatic field. When the current flow is low (i.e., before the onset of spark or corona discharge), these are related by the following equations tor two common forms of electrodes ... 

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